Wavelength converting particle, method for manufacturing wavelength converting particle, and light emitting diode containing wavelength converting particle

ABSTRACT

Provided are a wavelength converting particle, a method for manufacturing a wavelength converting particle, and a light-emitting diode containing a wavelength converting particle. The wavelength converting particle comprises a hybrid OIP nanocrystal that converts a wavelength of light generated by an excitation light source into a specified wavelength. Accordingly, it is possible to optically stabilize and improve color purity and light-emission performance without changes in a light-emitting wavelength range.

TECHNICAL FIELD

The present invention relates to a wavelength converting particle, amethod of manufacturing a wavelength converting particle, and alight-emitting diode (LED) containing a wavelength converting particle,and more particularly, to a wavelength converting nanoparticlecontaining a hybrid organic-inorganic perovskite (OIP) nanocrystal, amethod of manufacturing a wavelength converting nanoparticle containinga hybrid OIP nanocrystal, and an LED containing a wavelength convertingnanoparticle containing a hybrid OIP nanocrystal.

BACKGROUND ART

A light-emitting diode (LED) is a semiconductor device that convertselectric current into light and is mainly used as a light source of adisplay device. Such an LED exhibits very excellent properties in termsof a small size, low power consumption, a long lifetime, and a fastresponse time when compared to conventional light sources. In addition,an LED is environment-friendly because it does not release harmfulelectromagnetic waves such as ultraviolet light and also does not usemercury and other discharge gases. An LED is usually formed by combiningan LED light source using a wavelength converting particle such as aphosphor.

Conventionally, a quantum dot has been used as the wavelength convertingparticle. A quantum dot generates stronger light at a narrowerwavelength band than a typical phosphor. Light emission of a quantum dotis achieved when exited electrons transition from the conduction band tothe valence band. The same material has a wavelength that variesdepending on its size. A quantum dot may emit light of a shorterwavelength as the quantum dot decreases in size. Accordingly, it ispossible to obtain light of a desired wavelength region by adjusting thesize of the quantum dot.

A quantum dot may emit light even when an excited wavelength isarbitrarily selected. Accordingly, it is possible to observer light ofseveral colors at once by exciting several kinds of quantum dots with asingle wavelength. Also, since a quantum dot only transitions from aground vibration state of the conduction band to a ground vibrationstate of the valence band, a light emission wavelength is generallymonochromatic light.

A quantum dot is a nanocrystal of a semiconductor material having adiameter of about 10 nm. A vapor deposition method such as metal organicchemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) or achemical wet method in which precursors are inserted into an organicsolvent to grow a crystal is used to form the quantum dot. The chemicalwet method, which is a method of adjusting crystalline growth with anorganic solvent naturally coordinated on a quantum dot determinationsurface to serve as a dispersing agent when a crystal is grown, hasadvantages over a vapor deposition method such as MOCVD or MBE becausethe chemical wet method can adjust uniformity in size and form of ananocrystal through an easier and cheaper process.

However, a quantum dot has disadvantages in that the quantum dot is toounstable to be used as a wavelength converting material and has alimited color purity and luminescent effect. Accordingly, developing awavelength converting material that is more stable and has improvedcolor impurity and light emission performance is urgently required.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

The present invention is designed to solve the above problems and isdirected to providing a wavelength converting body that is opticallystable and has enhanced color purity and light emission performance, amanufacturing method therefor, and a light-emitting diode (LED)containing the same.

Technical Solution

One aspect of the present invention provides a wavelength convertingnanoparticle. The wavelength converting nanoparticle includes a hybridorganic-inorganic perovskite (OIP) nanocrystal that converts awavelength of light generated by an excitation light source into aspecified wavelength.

The hybrid OIP nanocrystal may include a hybrid OIP nanocrystalcharacterized by being capable of being dispersed in an organic solvent,may have a size ranging from 1 nm to 900 nm, and may have band gapenergy ranging from 1 eV to 5 eV.

The hybrid OIP wavelength converting nanoparticle may further include aplurality of organic ligands that surround the hybrid OIP nanocrystal.The organic ligands may include alkyl halides.

The hybrid OIP may include a structure of A₂BX₄, ABX₄, ABX₃, orA_(n−1)B_(n)X_(3n+1) (n is an integer ranging from 2 to 6). Here, A maybe organic ammonium, B may be a metallic material, and X may be ahalogen element. A may be (CH₃NH₃)_(n),((C_(x)H2_(x+1))_(n)NH₃)₂(CH₃NH₃)_(n),(RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (n is an integergreater than or equal to 1 and x is an integer greater than or equal to1), B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof, and X may be Cl, Br, I, or a combination thereof.

Another aspect of the present invention provides a manufacturing methodfor a wavelength converting nanoparticle. The manufacturing methodincludes preparing a first solution, which has a hybrid OIP dissolved ina protic solvent, and a second solution, which has an alkyl halidesurfactant dissolved in an aprotic solvent; and forming a nanoparticleby mixing the first solution with the second solution. Here, thewavelength converting nanoparticle includes a hybrid OIP nanocrystalthat converts a wavelength of light generated by an excitation lightsource into a specified wavelength.

The forming of a nanoparticle by mixing the first solution with thesecond solution may include adding the first solution to the secondsolution in drops. The hybrid OIP may include a structure of A₂BX₄,ABX₄, ABX₃, or A_(n−1)B_(n)X_(3n+1) (n is an integer ranging from 2 to6). Here, A may be organic ammonium, B may be a metallic material, and Xmay be a halogen element. A may be ((CH₃NH₃)_(n),((C_(x)H2_(x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂ (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃)_(n), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (n is an integergreater than or equal to 1 and x is an integer greater than or equal to1), B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof, and X may be Cl, Br, I, or a combination thereof.

Another aspect of the present invention provides a hybrid OIP nanowavelength converting layer. The wavelength converting layer includesthe above-described wavelength converting nanoparticle.

Another aspect of the present invention provides a nano wavelengthconverting body. The nano wavelength converting body includes theabove-described wavelength converting nanoparticle; a dispersion mediumconfigured to disperse the wavelength converting nanoparticle; and asealing member configured to seal the wavelength converting nanoparticleand the dispersion medium, wherein the wavelength converting particle isdispersed in the dispersion medium. The dispersion medium may be in aliquid state.

Still another aspect of the present invention provides a light-emittingdevice. The light-emitting device includes a base structure; at leastone excitation light source disposed on the base structure andconfigured to emit light of a predetermined wavelength; and a wavelengthconverting layer disposed along an optical path of the excitation lightsource and including the above-described wavelength convertingnanoparticle. The wavelength converting layer may include a hybrid OIPnano wavelength converting body including the wavelength convertingnanoparticle; a dispersion medium configured to disperse the wavelengthconverting nanoparticle; and a sealing member configured to seal thewavelength converting nanoparticle and the dispersion medium, whereinthe wavelength converting particle is dispersed in the dispersionmedium.

Adventageous Effects of the Invention

According to the present invention, it is possible to implement awavelength converting particle that is optically stable and has enhancedcolor purity and light emission performance without changes in alight-emitting wavelength band thereof due to a particle size becausethe wavelength converting particle contains a hybrid organic-inorganicperovskite nanocrystal.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a wavelength convertingnanoparticle containing a hybrid OIP nanocrystal according to anembodiment of the present invention.

FIG. 2 is a flowchart showing a manufacturing method for a wavelengthconverting nanoparticle containing a hybrid OIP nanocrystal according toan embodiment of the present invention.

FIG. 3 is a schematic diagram of a perovskite nanocrystalline structureaccording to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing a method of manufacturing awavelength converting nanoparticle containing a hybrid OIP nanocrystalthrough an inverse nano-emulsion method according to an embodiment ofthe present invention.

FIG. 5 shows a wavelength converting layer according to an embodiment ofthe present invention.

FIGS. 6A to 6E are cross-sectional views illustrating a sealing methodfor a wavelength converting body according to an embodiment of thepresent invention.

FIG. 7 is a cross-sectional view of a light-emitting diode (LED)according to an embodiment of the present invention.

FIG. 8 shows an LED according to another embodiment of the presentinvention.

FIG. 9 shows a fluorescent image obtained by photographing light that isemitted when ultraviolet light is emitted to a wavelength convertingmaterial of a manufactured example and hybrid OIP films according toComparative Example 1 and Comparative Example 2.

FIG. 10 is a schematic diagram of wavelength converting particlesaccording to the manufactured example and Comparative Example 1.

FIG. 11 shows images obtained by photographing photoluminescencematrices of the wavelength converting particles according to themanufactured example and Comparative Example 1 at normal temperature andlow temperature.

FIG. 12 shows a result graph obtained by photographing photoluminescenceof the wavelength converting particles according to the manufacturedexample and Comparative Example 1.

MODE OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings todescribe the present invention. The present invention may, however, beembodied in different forms and should not be construed as limited tothe embodiments set forth herein. Like reference numerals refer to likeelements throughout the specification.

<Wavelength Converting Particle>

A wavelength converting nanoparticle containing a hybrid OIP nanocrystalthat converts a wavelength of light generated by an excitation lightsource into a specified wavelength according to an embodiment of thepresent invention will be described below.

When light incident from the outside (incident light) reaches theabove-described hybrid OIP wavelength converting particle, thewavelength converting particle emits light converted in wavelength.Accordingly, a wavelength converting body functions to covert awavelength of light through the hybrid OIP wavelength convertingparticle. Hereinafter, a portion of the incident light having awavelength shorter than that of light emitted by the above-describedhybrid OIP wavelength converting particle is referred to as excitationlight. Also, a light source that emits the above-described excitationlight is referred to as an excitation light source.

FIG. 1 is a schematic diagram showing a wavelength convertingnanoparticle containing a hybrid OIP nanocrystal according to anembodiment of the present invention.

Referring to FIG. 1, a wavelength converting particle according to anembodiment of the present invention, which is a hybrid OIP nanoparticle,includes a hybrid OIP nanocrystal 21 having a lamellar structurecomposed of alternating organic and inorganic surfaces.

The nanocrystal may have a band gap adjustable by halogen elementsubstitution. The nanocrystal may have band gap energy ranging from 1 eVto 5 eV.

For example, the band gap may be adjusted by organic elementsubstitution or center metal substitution.

Such a hybrid OIP may include a structure of A₂BX₄, ABX₄, ABX₃, orA_(n−1)B_(n)X_(3n+1) (n is an integer ranging from 2 to 6). Here, A isan organic ammonium material, B is a metallic material, and X is ahalogen element. For example, A may be (CH₃NH₃)_(n),((C_(x)H2_(x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (n is an integergreater than or equal to 1 and x is an integer greater than or equal to1). B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof. In this case, the divalent transition metal may be,for example, Ge, Sn, Pb, Eu, or Yb. Also, the alkaline earth metal maybe, for example, Ca or Sr. Also, X may be Cl, Br, I, or a combinationthereof.

A wavelength converting nanoparticle 20 containing a hybrid OIPnanocrystal according to the present invention may additionally containa plurality of organic ligands 22 surrounding the hybrid OIP nanocrystal21. In this case, the organic ligands 22, which are used as asurfactant, may include alkyl halides. Accordingly, the alkyl halidesused as the surfactant to stabilize a surface of such a hybrid OIPseparated in the above-described manner become the organic ligandssurrounding a surface of the hybrid OIP nanocrystal.

When an alkyl halide surfactant has a short length, a nanocrystal formedtherewith has a large size and may have a size greater than 900 nm. Inthis case, there may be a fundamental problem in that excitons areseparated as free charges and disappear, instead of being used to emitlight, due to thermal ionization and charge carrier delocalization in alarge nanocrystal.

That is, the size of the hybrid OIP nanocrystal is inverselyproportional to the length of the alkyl halide surfactant used to formthe nanocrystal.

Accordingly, it is possible to adjust the size of the hybrid OIPnanocrystal to a certain size or smaller by using alkyl halides of acertain size or larger as the surfactant. For example, a hybrid OIPnanocrystal having a size ranging from 1 nm to 900 nm may be formed byusing octadecyl ammonium bromide as the alkyl halide surfactant.

FIG. 2 is a flowchart showing a manufacturing method for a wavelengthconverting nanoparticle containing a hybrid OIP nanocrystal according toan embodiment of the present invention.

Referring to FIG. 2, the manufacturing method for a wavelengthconverting nanoparticle containing a hybrid OIP nanocrystal may includepreparing a first solution having a hybrid OIP dissolved in a proticsolvent and a second solution having an alkyl halide surfactantdissolved in an aprotic solvent (S100) and forming a nanoparticle bymixing the first solution with the second solution (S200).

That is, the wavelength converting nanoparticle containing the hybridOIP nanocrystal according to an embodiment of the present invention maybe manufactured through an inverse nano-emulsion method.

In detail, first, the first solution having the hybrid OIP dissolved inthe protic solvent and the second solution having the alkyl halidesurfactant dissolved in the aprotic solvent are prepared (S100).

In this case, the protic solvent may include, but is not limited to,dimethylformamide, gamma butyrolactone, N-methylpyrrolidone, ordimethylsulfoxide.

Also, the hybrid OIP may be a material having a crystalline structure.For example, the hybrid OIP may have a structure of A₂BX₄, ABX₄, ABX₃,or A_(n−1)B_(n)X_(3n+1) (n is an integer ranging from 2 to 6).

Here, A is an organic ammonium material, B is a metallic material, and Xis a halogen element.

For example, A may be (CH₃NH₃)_(n),((C_(x)H2_(x+1))_(n)NH₃)₂(CH₃NH₃)_(n),(RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃)_(n), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (n is an integergreater than or equal to 1 and x is an integer greater than or equal to1). Also, B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof. In this case, the divalent transition metal may be,for example, Ge, Sn, Pb, Eu, or Yb. Also, the alkaline earth metal maybe, for example, Ca or Sr. Also, X may be Cl, Br, I, or a combinationthereof.

FIG. 3 is a schematic diagram of a perovskite nanocrystalline structureaccording to an embodiment of the present invention.

Referring to FIG. 3, it can be seen that the perovskite nanocrystallinestructure according to an embodiment of the present invention includesorganic ammonium and halides.

Such a perovskite may be prepared by combining AX and BX₂ at a certainratio. That is, the first solution may be formed by dissolving AX andBX₂ in a protic solvent at a certain ratio. For example, a firstsolution having an A₂BX₃ hybrid OIP dissolved therein may be prepared bydissolving AX and BX₂ in the protic solvent at a ratio of 2:1.

Also, the aprotic solvent may include, but is not limited to,dichloromethane, trichlorethylene, chloroform, chlorobenzene,dichlorobenzene, styrene, dimethylformamide, dimethylsulfoxide, xylene,toluene, cyclohexene, or isopropyl alcohol.

Also, the alkyl halide surfactant may have a structure of alkyl-X. Inthis case, a halogen corresponding to X may include Cl, Br, or I. Inthis case, the structure of alkyl-X may include, but is not limited to,acyclic alkyl having a structure of C_(n)H_(2n−1), primary alcohol,secondary alcohol, and tertiary alcohol having a structure ofC_(n)H_(2n−1)OH or the like, alkylamine having a structure of alkyl-N(e.g., hexadecyl amine or 9-Octadecenylamine 1-Amino-9-octadecene(C₁₉H₃₇N)), p-substituted aniline, phenyl ammonium, and fluorineammonium.

Subsequently, a nanoparticle is formed by mixing the first solution withthe second solution (S200).

The forming of a nanoparticle by mixing the first solution with thesecond solution preferably includes adding the first solution to thesecond solution in drops. In this case, the second solution may beagitated. For example, the nanoparticle may be synthesized by slowlyadding the first solution having the OIP dissolved therein to the secondsolution having the alkyl halide surfactant dissolved therein, which isbeing strongly agitated, in drops.

In this case, when the first solution is mixed with the second solutiondrop by drop, the OIP is precipitated from the second solution becauseof a solubility difference therebetween. Also, the alkyl halidesurfactant stabilizes a surface of the OIP precipitated from the secondsolution to generate a well-dispersed OIP nanocrystal (OIP-NC).Accordingly, it is possible to manufacture a wavelength convertingnanoparticle containing a hybrid OIP nanocrystal that includes an OIP-NCand a plurality of alkyl halide organic ligands surrounding the OIP-NC.

Such an OIP-NC may be controlled in size by adjusting a length or shapefactor of the alkyl halide surfactant. For example, the adjustment ofthe shape factor may be controlled through a tapered or an inverselytriangular surfactant.

It is preferable that an OIP-NC generated in the above manner have asize ranging from 1 nm to 900 nm. When the OIP-NC is formed to have asize greater than 900 nm, there may be a fundamental problem in thatexcitons are separated as free charges and disappear, instead of beingused to emit light, due to thermal ionization and charge carrierdelocalization in a large nanocrystal.

FIG. 4 is a schematic diagram showing a method of manufacturing awavelength converting nanoparticle containing a hybrid OIP nanocrystalthrough an inverse nano-emulsion method according to an embodiment ofthe present invention.

Referring to FIG. 4A, the first solution having the hybrid OIP dissolvedin the protic solvent is added in drops to the second solution havingthe alkyl halide surfactant dissolved in the aprotic solvent.

In this case, the protic solvent may include, but is not limited to,dimethylformamide, gamma butyrolactone, N-methylpyrrolidone, ordimethylsulfoxide.

In this case, the hybrid OIP may include a structure of A₂BX₄, ABX₄,ABX₃, or A_(n−1)B_(n)X_(3n+1) (n is an integer ranging from 2 to 6).Here, A is an organic ammonium material, B is a metallic material, and Xis a halogen element. For example, A may be (CH₃NH₃)_(n), ((C_(x)H²_(x+1))_(n)NH₃)₂(CH₃NH₃)_(n),(RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂, (CF₃NH₃),(CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (n is an integergreater than or equal to 1). Also, B may be a divalent transition metal,a rare earth metal, an alkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb,Bi, Po, or a combination thereof. In this case, the divalent transitionmetal may be, for example, Ge, Sn, Pb, Eu, or Yb. Also, the alkalineearth metal may be, for example, Ca or Sr. Also, X may be Cl, Br, I, ora combination thereof.

A structure of the perovskite may be formed by combining AX and BX₂ at acertain ratio. For example, a first solution having an A₂BX₃ hybrid OIPdissolved therein may be prepared by dissolving AX and BX₂ in a proticsolvent at a ratio of 2:1.

When A is CH₃NH₃ and X is Br as an example of a composition of AX,CH₃NH₃Br may be obtained by dissolving CH₃NH₂ (methylamine) and HBr(hydroiodic acid) in a nitrogen atmosphere and evaporating a solvent.

Referring to FIG. 4B, when the first solution is added to the secondsolution, the hybrid OIP is precipitated from the second solutionbecause of a solubility difference therebetween. An alkyl halidesurfactant surrounds the hybrid OIP and stabilizes a surface of thehybrid OIP. Thus, the wavelength converting nanoparticle 20 containing ahybrid OIP nanocrystal containing a well-dispersed OIP-NC is generated.In this case, the surface of the hybrid OIP nanocrystal is surrounded byorganic ligands, which are alkyl halides.

The wavelength converting nanoparticle containing the hybrid OIPnanocrystal may be obtained by applying heat to selectively evaporate aprotic solvent containing the wavelength converting nanoparticle 20containing the hybrid OIP nanocrystal, which is dispersed in an aproticsolvent having the alkyl halide surfactant dissolved therein, or byadding a co-solvent capable of being mixed with both of the proticsolvent and the aprotic solvent to selectively extract the proticsolvent containing the nanoparticle from the aprotic solvent.

The above-described wavelength converting nanoparticle may be dispersedin all organic solvents. Thus, the wavelength converting nanoparticlemay be applied to various electronic devices because a size, alight-emitting wavelength spectrum, a ligand, and a constituent elementthereof can be easily adjusted.

<Wavelength Converting Layer>

A nano wavelength converting layer including a hybrid OIP nanocrystalaccording to an embodiment of the present invention will be describedbelow.

FIG. 5 shows a wavelength converting layer according to an embodiment ofthe present invention.

Referring to FIG. 5, the wavelength converting layer according to anembodiment of the present invention is a layer that includes thewavelength converting nanoparticle 20 containing a hybrid OIPnanocrystal according to an embodiment of the present invention.

Since the wavelength converting particle has the same configuration andfunction as those described in the section <Wavelength convertingparticle>, reference will be made to the above description.

The above-described wavelength converting layer may be formed as apolymer resin in which wavelength converting particles 20 are uniformlydispersed. In this case, the polymer resin serves as a dispersion mediumthat disperses the wavelength converting particles 20. Any transparentmedium that is not changed by light, does not reflect and absorb light,and does not affecting performance of the wavelength converting particle20 may be used as the dispersion material.

As an example, it is preferable that the dispersion material be made ofa material that has high light resistance or moisture resistance and isnot changed in color or quality by excitation light or the like, such asan epoxy resin or silicone.

The above-described dispersion medium may be in a liquid state. When theabove-described dispersion medium is in the liquid state, the wavelengthconverting particle 20 may be manufactured to be applied to variousdevices. Also, when the above-described dispersion medium is in theliquid state and the above-described wavelength converting particlecontains a plurality of organic ligands surrounding the hybrid OIPnanocrystal, the wavelength converting particle may be applied to adevice without separate ligand purification. Thus, it is possible tosimplify a process thereof.

<Wavelength Converting Body>

A manufacturing method for a wavelength converting body according to anembodiment of the present invention will be described below.

First, a wavelength converting particle is prepared.

Since the wavelength converting particle has the same configuration andfunction as those described in the section <Wavelength convertingparticle>, reference will be made to the above description.

Subsequently, the above-described wavelength converting particle isdispersed in a dispersion medium.

The wavelength converting particle is dispersed in the above-describeddispersion medium. The dispersion medium may be in the liquid state.When the dispersion medium is in the liquid state and the dispersionmedium and the wavelength converting particle dispersed in thedispersion medium are sealed by a sealing member, which will bedescribed below, the dispersion medium and the wavelength convertingparticle are not limited by a shape of the sealing member and may beapplied to various devices. For example, the dispersion medium may be anepoxy resin or silicone. It is preferable that the dispersion medium bemade of a material that is not changed in color or quality by excitationlight or the like because the wavelength converting particle receivesexcitation light and emits wavelength-converted light.

Subsequently, the wavelength converting particle and the dispersionmedium are sealed with the sealing member.

FIGS. 6A to 6E are cross-sectional views illustrating a sealing methodfor a wavelength converting body according to an embodiment of thepresent invention. Referring to FIG. 6A, a first sealing member 10 a anda second sealing member 10 b are stacked.

A polymer or silicone that is not corroded by a dispersion medium 30having the wavelength converting particle 20 dispersed therein may usedas a sealing member. In particular, a polymer resin may be adhered to anobject when it is heated, and thus a pack-type wavelength convertingbody into which the dispersion medium 30 having the wavelengthconverting particle 20 dispersed therein is injected may be formed byadhering sheet-type polymer resin to the dispersion medium 30 through athermal adherence process.

Referring to FIG. 6B, the first sealing member 10 a and the secondsealing member 10 b may be adhered to each other through the thermaladherence process by heating the first sealing member 10 a and thesecond sealing member 10 b at one side 1 in order to prevent theabove-described wavelength converting particle 20 and dispersion medium30 from leaking through the sealing members 10 a and 10 b. However, anadherence process other than the thermal adherence process may be usedwhen the above-described wavelength converting particle 20 anddispersion medium 30 do not leak.

Referring to FIG. 6C, the dispersion medium 30 having the wavelengthconverting particle 20 dispersed therein is injected between the firstsealing member 10 a and the second sealing member 10 b at the other sideat which the sealing members are not adhered to each other.

Referring to FIG. 6D, the dispersion medium 30 having the wavelengthconverting material 20 dispersed therein is sealed with the sealingmembers 10 a and 10 b by adhering the first sealing member 10 a and thesecond sealing member 10 b at the other side 1′ through the thermaladherence process.

Referring to FIG. 6E, it can be seen that a hybrid OIP nano wavelengthconverting body 400 in which the dispersion medium 30 having thewavelength converting material 20 dispersed therein is sealed with thesealing members 10 is formed. The above-described hybrid OIP nanowavelength converting body 400 may be advantageously applied to alight-emitting device without needing a separate ligand purificationprocess by dispersing the wavelength converting nanoparticle 20containing a hybrid OIP nanocrystal, which is a wavelength convertingmaterial, in the dispersion medium 30 and sealing the wavelengthconverting nanoparticle 20 dispersed in the dispersion medium 30.Accordingly, it is possible to prevent oxidation of the wavelengthconverting particle due to ligand purification and thus exhibit a highcolor purity and luminescent effect when the hybrid OIP nano wavelengthconverting body 400 is applied to a light-emitting device. It is alsopossible to simplify a process thereof.

<Light-Emitting Device>

FIG. 7 is a cross-sectional view of a light-emitting device according toan embodiment of the present invention.

Referring to FIG. 7, a light-emitting device according to an embodimentof the present invention includes a base structure 100, at least oneexcitation light source 200 disposed on the base structure 100 andconfigured to emit light of a predetermined wavelength, and a wavelengthconverting layer 400B disposed along an optical path of the excitationlight source 200 and containing the wavelength converting particle 20.

The base structure 100 may be a package frame or a base substrate. Whenthe base structure 100 is a package frame, the package frame may includea base substrate. The base substrate may be a sub-mount substrate or alight-emitting diode (LED) wafer. The LED wafer indicates a state inwhich an LED element is formed on a wafer between, which is a statebefore the LED is separated in units of an LED chip. The base substratemay be a silicon substrate, a metal substrate, a ceramic substrate, or aresin substrate.

The base structure 100 may be a packet lead frame or a package pre-moldframe. The base structure 100 may include bonding pads (not shown). Thebonding pads may contain Au, Ag, Cr, Ni, Cu, Zn, Ti, Pd, or the like.External connection terminals (not shown) connected to the bonding padsmay be disposed at an outer surface of the base structure 100. Thebonding pads and the external connection terminals may be included in apackage lead frame.

The excitation light source 200 is located on the base structure 100. Itis preferable that the excitation light source 200 emit light of awavelength shorter than a light-emitting wavelength of a wavelengthconverting particle of the wavelength converting layer 400B.

The excitation light source 200 may be any one of an LED and a laserdiode. Also, when the base structure 100 is an LED wafer, thepositioning of the excitation light source may be omitted. For example,a blue LED may be used as the excitation light source 200, and a galliumnitride-based LED that emits blue light of a wavelength ranging from 420nm to 480 nm may be used as the blue LED.

As shown in FIG. 8, a first encapsulation part 300 may be formed bypouring an encapsulation material for encapsulating the excitation lightsource 200 over the excitation light source 200. The first encapsulationpart 300 may serve as a protective film and also serve to encapsulatethe excitation light source 200. Also, when the wavelength convertinglayer 400B is located over the first encapsulation part 300, a secondencapsulation part 500 may be additionally formed to protect and fix thewavelength converting layer 400B. The encapsulation material may includeat least one of an epoxy, a silicone, acrylic polymers, a glass,carbonate polymers, and mixtures thereof.

The first encapsulation part 300 may be formed using various methodssuch as a compression molding method, a transfer molding method, adotting method, a blade coating method, a screen coating method, a dipcoating method, a spin coating method, a spray method, or an inkjetprinting method. However, the first encapsulation part 300 may beomitted.

Since the wavelength converting layer 400B has the same configurationand function as those described in the sections <Wavelength convertinglayer> and <Wavelength converting particle>, reference will be made tothe above description.

As shown in FIG. 7, the second encapsulation part 500 may be formed bypouring an encapsulation material for encapsulating the wavelengthconverting layer 400B over the wavelength converting layer 400B. Thesecond encapsulation part 500 may be formed using the same material asthe first encapsulation part 300 through the same method as the firstencapsulation part 300.

The light-emitting device may be applied to a lighting unit, a backlightunit, or the like as well as a device for emitting light.

FIG. 8 shows an LED according to another embodiment of the presentinvention.

Referring to FIG. 8, the wavelength converting layer 400 may include awavelength converting body 400A, as shown in FIG. 6.

Since the wavelength converting body 400A has the same configuration andfunction as those described in the sections <Wavelength converting body>and <Wavelength converting particle>, reference will be made to theabove description.

According to an embodiment of the present invention, the limit-emittingdevice has been shown as a unit cell. However, when the base structureis a sub-mount substrate or a LED wafer, multiple LED chips, each havinga wavelength converting layer formed therein, may be located on thesub-mount substrate and the LED wafer, and the sub-mount substrate orthe LED wafer may be cut and processed in units of a unit cell.

For a better understanding of the present invention, a preferredexperimental example will be described below. However, the followingexperimental example is merely intended to facilitate an understandingof the present invention, and thus the present invention is not limitedthereto.

MANUFACTURED EXAMPLE Manufacture of Wavelength Converting Particle

A wavelength converting nanoparticle containing a hybrid OIP nanocrystalaccording to an embodiment of the present invention was formed. Thewavelength converting nanoparticle was formed through an inversenano-emulsion method.

In detail, a first solution was prepared by dissolving a hybrid OIP in aprotic solvent. In this case, dimethylformamide was used as the proticsolvent, and (CH₃NH₃)₂PbBr₄ was used as the hybrid OIP. In this case,(CH₃NH₃)₂PbBr₄ was formed by mixing CH₃NH₃Br and PbBr₂ at a ratio of2:1.

Subsequently, a second solution having an alkyl halide surfactantdissolved in an aprotic solvent was prepared. In this case, toluene wasused as the aprotic solvent, and octadecylammonium bromide(CH₃(CH₂)_(i7)NH₃Br) was used as the alkyl halide surfactant.

Subsequently, a wavelength converting particle containing a hybrid OIPnanocrystal was formed by slowly adding the first solution to the secondsolution, which is being strongly agitated, in drops.

COMPARATIVE EXAMPLE 1

A thin-film type hybrid OIP (an OIP film) was manufactured.

In detail, a thin film of (CH₃NH₃)₂PbBr₄ was manufactured by dissolving(CH₃NH₃)₂PbBr₄ in dimethylformamide, which was a protic solvent, tomanufacture a first solution and then performing spin-coating on a glasssubstrate with the first solution.

COMPARATIVE EXAMPLE 2

A thin-film type hybrid OIP (an OIP film) was manufactured.

In detail, a thin film of (CH₃NH₃)₂PbCl₄ was manufactured by dissolving(CH₃NH₃)₂PbCl₄ in dimethylformamide, which was a protic solvent, tomanufacture a first solution and then performing spin-coating on a glasssubstrate with the first solution.

EXPERIMENTAL EXAMPLE

FIG. 9 shows a fluorescent image obtained by photographing light that isemitted when ultraviolet light is emitted to a wavelength convertingmaterial of the manufactured example and hybrid OIP films according toComparative Example 1 and Comparative Example 2.

Referring to FIG. 9, it can be seen that the wavelength convertingparticle having the form of a nanoparticle according to the manufacturedexample emits very bright green light while the hybrid OIPs having theform of a thin film other than a nanoparticle emit dark light.

Also, it can be seen, as a result of measuring a photoluminescencequantum yield (PLQY), that the hybrid OIP particle according to themanufactured example exhibit very high values.

Conversely, the thin-film type hybrid OIPs according to ComparativeExample 1 and Comparative Example 2 exhibit low PLQY values of about 1%.

FIG. 10 is a schematic diagram of wavelength converting particlesaccording to the manufactured example and Comparative Example 1.

FIG. 10A is a schematic diagram of the wavelength converting particlesaccording to Comparative Example 1, and FIG. 10B is a schematic diagramof the wavelength converting particles according to the manufacturedexample. Referring to FIG. 10A, the wavelength converting particlesaccording to Comparative Example 1 are in the form of a thin-film.Referring to FIG. 10B, the wavelength converting particles according tothe manufactured example are in the form of a nanoparticle 21.

FIG. 11 shows images obtained by photographing photoluminescencematrices of wavelength converting particles according to themanufactured example and Comparative Example 1 at normal temperature andlow temperature.

FIG. 11A shows the image obtained by photographing the photoluminescencematrix of the thin-film type hybrid OIP (OIP film) according toComparative Example 1 at low temperature (70 K), and FIG. 11B shows theimage obtained by photographing the photoluminescence matrix of thethin-film type hybrid OIP (OIP film) according to Comparative Example 1at room temperature.

FIG. 11C shows the image obtained by photographing the photoluminescencematrix of the wavelength converting nanoparticle containing the hybridOIP nanocrystal according to the manufactured example at low temperature(70 K), and FIG. 11D shows the image obtained by photographing thephotoluminescence matrix of the wavelength converting nanoparticlecontaining the hybrid OIP nanocrystal according to the manufacturedexample at room temperature.

Referring to FIGS. 11A to 11D, it can be seen that the wavelengthconverting nanoparticle containing the hybrid OIP nanocrystal accordingto the manufactured example exhibits higher color purity than thethin-film type hybrid OIP (OIP film) according to Comparative Example 1while exhibiting photoluminescence at the same position thereas. It canbe also seen that the OIP-NC film according to the manufactured exampleexhibits photoluminescence with the same level of color purity at roomtemperature and low temperature and also does not decrease inluminescence intensity. Conversely, the thin-film type hybrid OIPaccording to Comparative Example 1 has different color purity levels andluminescence positions at room temperature and low temperature and alsoexhibits low luminescence intensity at room temperature because excitonsthereof are separated as free charges and disappear, instead of beingused to emit light, due to thermal ionization and charge carrierdelocalization.

FIG. 12 shows a result graph obtained by photographing photoluminescenceof the wavelength converting particles according to the manufacturedexample and Comparative Example 1.

Referring to FIG. 12, it can be seen that, when the hybrid OIPnanoparticle according to the manufactured example is located in asolution, that is, in the liquid state, the hybrid OIP nanoparticleexhibits higher color purity than the conventional hybrid OIP accordingto Comparative Example 1 while exhibiting photoluminescence at the sameposition thereas.

The wavelength converting particle containing the nanocrystal includingthe OIP according to the present invention may have a hybrid OIPnanocrystal having a crystalline structure obtained by combining FCC andBCC formed therein, have a lamellar structure composed of alternatingorganic and inorganic surfaces, and exhibit a high color purity becauseexcitons are bound to the inorganic surface.

In a nanocrystal having a size ranging from 10 nm to 300 nm, an excitondiffusion length may decrease and also exciton binding energy mayincrease. Thus, it is possible to prevent disappearance of excitons dueto thermal ionization and charge carrier delocalization such thatluminescent efficiency at room temperature is high.

Furthermore, by synthesize a nanocrystal having a three-dimensionalstructure unlike the OIP, it is possible to increase exciton bindingenergy to enhance luminescent efficiency while increasing durability andstability.

Also, according to the manufacturing method for a wavelength convertingparticle containing a hybrid OIP nanocrystal according to the presentinvention, it is possible to synthesize a wavelength convertingnanoparticle containing a hybrid OIP nanocrystal adjusted in sizedepending on a length and size of an alkyl halide surfactant.

While the present invention has been particularly shown and describedwith reference to preferred embodiments thereof, the present inventionis not limited to the embodiments, and various modifications and changesmay be made therein by those skilled in the art without departing fromthe sprit and scope of the present invention.

<Description of reference numerals> 1: one side of sealing member 1′:other side of sealing member 10: sealing member 20: wavelengthconverting particle 30: dispersion medium 100: base structure 200:excitation light source 300: first sealing part 400B: wavelengthconverting layer 400A: wavelength converting body 500: second sealingpart

1. A hybrid organic-inorganic perovskite (OIP) wavelength convertingnanoparticle comprising a hybrid OIP nanocrystal that converts awavelength of light generated by an excitation light source into aspecified wavelength.
 2. The hybrid OIP wavelength convertingnanoparticle of claim 1, wherein the hybrid OIP nanocrystal includes ahybrid OIP nanocrystal characterized by being capable of being dispersedin an organic solvent.
 3. The hybrid OIP wavelength convertingnanoparticle of claim 1, wherein the hybrid OIP nanocrystal has a sizeranging from 1 nm to 900 nm.
 4. The hybrid OIP wavelength convertingnanoparticle of claim 1, wherein the hybrid OIP nanocrystal has band gapenergy ranging from 1 eV to 5 eV.
 5. The hybrid OIP wavelengthconverting nanoparticle of claim 1, further comprising a plurality oforganic ligands that surround the hybrid OIP nanocrystal.
 6. The hybridOIP wavelength converting nanoparticle of claim 5, wherein the organicligands include alkyl halides.
 7. The hybrid OIP wavelength convertingnanoparticle of claim 1, wherein: the hybrid OIP includes a structure ofA₂BX₄, ABX₄, ABX₃, or A_(n−1)B_(n)X_(3n+1) (n is an integer ranging from2 to 6); and A is organic ammonium, B is a metallic material, and X is ahalogen element.
 8. The hybrid OIP wavelength converting nanoparticle ofclaim 7, wherein: A is (CH₃NH₃)_(n),((C_(x)H2_(x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (n is an integergreater than or equal to 1 and x is an integer greater than or equal to1); B is a divalent transition metal, a rare earth metal, an alkalineearth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or a combinationthereof; and X is Cl, Br, I, or a combination thereof.
 9. Amanufacturing method for a wavelength converting nanoparticle containinga hybrid OIP nanocrystal that converts a wavelength of light generatedby an excitation light source into a specified wavelength, themanufacturing method comprising: preparing a first solution having ahybrid OIP dissolved in a protic solvent and a second solution having analkyl halide surfactant dissolved in an aprotic solvent; and forming ananoparticle by mixing the first solution with the second solution. 10.The manufacturing method of claim 9, wherein the forming of ananoparticle by mixing the first solution with the second solutioncomprises adding the first solution to the second solution in drops. 11.The manufacturing method of claim 9, wherein: the hybrid OIP includes astructure of A₂BX₄, ABX₄, ABX₃, or A_(n−1)B_(n)X_(3n+1) (n is an integerranging from 2 to 6); and A is organic ammonium, B is a metallicmaterial, and X is a halogen element.
 12. The manufacturing method ofclaim 11, wherein: A is ((CH₃NH₃)_(n),((C_(x)H2_(x+1))_(n)NH₃)₂(CH₃NH₃)_(n),(RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (n is an integergreater than or equal to 1 and x is an integer greater than or equal to1); B is a divalent transition metal, a rare earth metal, an alkalineearth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or a combinationthereof; and X is Cl, Br, I, or a combination thereof.
 13. A hybrid OIPnano wavelength converting layer containing the wavelength convertingnanoparticle of claim
 1. 14. A hybrid OIP nano wavelength convertingbody comprising: the wavelength converting nanoparticle of claim 1; adispersion medium configured to disperse the wavelength convertingnanoparticle; and a sealing member configured to seal the wavelengthconverting nanoparticle and the dispersion medium, wherein thewavelength converting particle is dispersed in the dispersion medium.15. The hybrid OIP nano wavelength converting body of 14, wherein thedispersion medium is in a liquid state.
 16. A light-emitting devicecomprising: a base structure; at least one excitation light sourcedisposed on the base structure and configured to emit light of apredetermined wavelength; and a wavelength converting layer disposedalong an optical path of the excitation light source and including thewavelength converting nanoparticle of claim
 1. 17. The light-emittingdevice of claim 16, wherein the wavelength converting layer comprises ahybrid OIP nano wavelength converting body comprising: the wavelengthconverting nanoparticle; a dispersion medium configured to disperse thewavelength converting nanoparticle; and a sealing member configured toseal the wavelength converting nanoparticle and the dispersion medium,wherein the wavelength converting particle is dispersed in thedispersion medium.